Generally, as a sheet bunch processing apparatus (post-processing apparatus) is widely known an apparatus which collects a plurality of sheets discharged from an image formation apparatus on a processing tray, performs post-processing such as binding processing with a binding processing apparatus, and carries out to a stack tray on the downstream side to store. Further, an apparatus for performing binding processing with staples is widely used, as the binding processing apparatus used in such a sheet bunch processing apparatus. However, since sheets are not peeled easily and there is also the problem processing bound documents (shredder cutting and the like), various binding processing apparatuses have been proposed which do not use metal needles.
For example, Patent Document 1 discloses a sheet bunch processing apparatus configured to collect sheets on a processing tray from a sheet discharge outlet of an image formation apparatus, and cause an operator to select whether to perform staple binding processing or perform needleless binding processing on the sheet bunch. The needleless binding processing in the sheet bunch processing apparatus as disclosed in Patent Document 1 is performed by the so-called press binding processing for using the apparatus (hereinafter, described as needleless binding apparatus) having a pair of concavo-convex-shaped pressurizing surfaces that mutually mesh, nipping a sheet bunch between a pair of pressurizing surfaces to bring into press intimate contact, and thereby binding the sheet bunch. More specifically, the needleless binding processing is performed by transporting a sheet bunch in a direction (sheet width direction) orthogonal to a sheet discharge direction to position in between a pair of pressurizing surfaces, performing the press binding processing on the sheet bunch, and then, carrying out the sheet bunch in the same direction as the sheet discharge direction.